In accordance with the conventional mode of operation of pressured steam drum type steam generating systems, water in water tubes, the latter commonly being referred to as risers, is heated in order to thereby generate a two-phase mixture of steam and water. This two-phase mixture is then made to flow from such risers to a steam drum. Continuing, the steam that enters such a steam drum is designed to be intimately mixed with large and possibly variable amounts of water.
Installed within such a steam drum are separators and other devices that are designed to be operative to effect therewith the separation of such steam from such water, prior to such steam being made to leave such steam drum and being made to enter a superheater. To this end, in addition to such separators, such a steam drum commonly may embody internal baffles that are designed to be operative for purposes of effecting therewith a change in the direction of flow of such steam and water mixture, as well as impellers and/or moisture coalescers such as, by way of exemplification, screen and corrugated plate final dryers. Such separators and such other devices often are used singly, but more commonly are employed in consort in order to thereby effect therewith the separation and purification of such steam, so that most, if not all, of the impurities that may be entrained in such steam are thus removed from such steam before the latter is made to leave such a steam drum.
It is necessary that such separators and such other devices be designed with various factors in mind. For example, such separation and such purification must be performed therewith within a matter of seconds and under a variety of different operating condition. To this end, such a steam/water mixture may be flowing at any of a variety of different velocities and/or may be at any of a variety of different pressures. In addition, the pressure drop across such separators and such other devices should be kept relatively low in order to thereby minimize the effect such separators and such other devices have on the circulation of the water through the steam generating system and/or on the water level controls of the steam generating system.
Continually, also the space that is required in order to thereby accommodate such separators and such other devices in such a steam drum for purposes of effecting therewith the separation of and the purification of such steam in such a steam drum must be taken into account in determining the sizing of such a steam drum. To this end, the diameter and the length of such a steam drum must necessarily be made to be sufficient in order to thereby provide accessibility for purposes of effecting the installation as well as permitting inspection of such separators and such other devices, and to also provide for the processing of the maximum flows of water and steam therethrough. Indeed, designing such a steam drum such that the latter has sufficient drum diameter and length in order to thereby provide such accessibility, while still providing such a steam drum that embodies a reasonable size has at times proven to be a significant challenge.
It is also well recognized by those skilled in the art that water in such steam-water mixture frequently contains dissolved and suspended salts. Thus, any water that is not separated from such steam-water mixture will also include such dissolved and suspended salts, which will appear as a solids impurity in such steam. If such water remains combined with such steam leaving such a steam drum, when the moisture, i.e., such water, is evaporated in the superheater, such solids impurity will remain in the superheated steam that is made to flow to a turbine or to such other steam driven apparatus. To this end, such steam having such a solids impurity entrained therewith can have a detrimental effect on the operation and service life of such a turbine or such other steam driven apparatus.
One exemplary innovative technique for effecting the separation of water from steam in the steam drum of a steam generating system is disclosed in U.S. Pat. No. 5,320,652, all rights to which are assigned to the same assignee as are all of the rights in the present patent application, which is incorporated herein by reference in its entirety. Continuing, the '652 U.S. patent discloses an improved separator that can be installed within a relatively small amount of space in the steam drum of a steam generating system, such as to be operative to quickly effect the removal therewith of substantial quantities of water from a mixture of steam-water that is flowing through the steam drum of such a steam generating system with a relatively low-pressure loss. The separator that is disclosed in the '652 U.S. patent is deemed to comprise a substantial improvement over the conventional separator technology that existed at that time, although the separator technology to which the '652 U.S. patent is directed has not been widely implemented since the issuance of the '652 U.S. patent. Rather, another somewhat simplified, but highly reliable, separator technology is the one that remains in wide use even today. This widely used separator is sometimes referred to by those skilled in the art as a standard separator. Such a standard separator embodies a core as well as a limited number of spinner blades, e.g., 4 spinner blades, and lacks the diffuser section and other superstructure that the '652 U.S. patent embodies wherein such diffuser section and such other superstructure are suitably located above the housing 28 of the separator that is described and illustrated in the '652 U.S. patent. Such a standard separator has now served the industry well for many years.
However, a need still exist for a new and improved separator technology that would be operative to facilitate the more efficient or the more effective removal of a liquid from a vapor, such as the removal of water from steam, and that could be implemented through the use of a separator without the need for employing the relatively complex superstructure that is required by the separator technology that is described and illustrated in the '652 U.S. patent.